Spatial and temporal variations of surface water quality of Batticaloa Lagoon with the special reference to coastal line in Sri Lanka

Batticaloa lagoon is an inland body of water plays a significant role to uplift the standard of living of people, especially fishing community in Batticaloa district. However, lagoon water pollution has become a growing menace to human society and natural ecosystems in recent decades. Hence, it is vital to understand the spatial and temporal variability of pollutants within aquatic systems. Therefore, this study aimed to investigate the spatial and temporal variations of surface water of Batticaloa lagoon. This study was carried out from November, 2013 to June, 2014. Batticaloa lagoon was divided into three divisions based on anthropogenic activities where twenty sampling points were randomly selected from these divisions and water samples were taken monthly. Physico-chemical parameters such as temperature, pH, EC and TDS were measured at sampling points while TSS, TS, DO, BOD, phosphate, nitrate and turbidity were measured at laboratory. Data were analyzed statistically to interpret the results. Results showed that all the quality parameters tested except turbidity exceed the standard levels for aquatic life while DO falls within the acceptable range. There were high range in tested parameters, temperature ranged between 27.2˚C to 32.5˚C, pH 6.4 - 9.2, EC 600µS/cm - 1700μS/cm, TDS 296mg/l - 873mg/l, TSS 13mg/l – 35mg/l, phosphate 0.19mg/l - 0.76mg/l, nitrate 0.97mg/l - 2.60mg/l, DO 4.64mg/l - 7.12mg/l, BOD5 4.13mg/l - 8.66mg/l and turbidity 6.6NTU - 13.9NTU. Phosphate and nitrate levels significantly (p<0.05) varied among the divisions. Further, temperature, pH, EC, TDS, TS, DO and phosphate were high during dry season while TSS, BOD, nitrate and turbidity were high during wet season. The variations of EC, TDS, TS, TSS, BOD and turbidity between wet and dry seasons were also significant. The study concludes that, the Batticaloa lagoon water has been polluted. However, pollution level is not severe. Therefore, measures should be taken to prevent the further pollution of Batticaloa lagoon.